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Vinyl PCB Resist 



Make] Projects 



Vinyl PCB Resist 

Written By: Chris Connors 



TOOLS: 

CNC vinyl cutter/plotter (1) 
Gloves (1) 
Safety glasses (1) 

Tray or jar (1) 

such as glass or ceramic 

Tweezers or other sharp tool (1) 







PARTS: 

Adhesive-backed vinyl sheets (1) 





Copper circuit board blank (1) 

Kitchen scrub pad, sandpaper, or steel 
wool (1) 



Masking tape or transfer tape (1) 





Etching chemicals (1) 

such as fe or muriatic 





SUMMARY 

There are lots of ways to etch a circuit board, but all of them create a path for electricity by 
preserving and removing portions of the copper coating on the board. You might have tried 
drawing a circuit on copper with a pen or grease pencil, or silk-screening it, or transferring 
toner from a laser printer, and then chemically etching the board. A substance used in this 
way is called a resist because it resists the etchant and protects the copper. 

One of the easiest and most reliable resists I've found is adhesive-backed vinyl produced on 
a sign cutter. This is done by sticking your circuit trace image directly onto the board, and 
then immersing the board in a chemical bath. The exposed copper is removed, leaving just 



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Vinyl PCB Resist 

the copper traces you want for your circuit. Here's how I do it. 



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Vinyl PCB Resist 



Step 1 — Get a circuit board design. 




• You can design your own circuit 
traces, or use existing artwork of 
proven designs. Search the Open 
Circuits wiki, Adafruit's Github 
repository, and hobbyist websites 
like diystompboxes.com to get a 
taste of what's out there for free. 

• And remember, you can also 
transform schematic diagrams into 
circuit board layouts using free 
software tools. 

• We designed this board as a 
supersized version of the MAKE 
Learn to Solder robot pin . It's got 
huge traces, but people also use 
this method to make fine traces. 



Step 2 — Cut your design in vinyl. 




• Convert your board design into an 
image format your vinyl cutter can 
use. If you bring the design to a 
shop, they'll tell you what formats 
to use. 

• Cut the design into the vinyl with 
the vinyl cutter. If you're using a 
service, make sure the cut is 
scaled accurately. If the design 
isn't the right size, your parts may 
not fit properly. 



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Vinyl PCB Resist 



Step 3 — "Weed" your vinyl stickers. 




• Carefully remove the unwanted 
vinyl bits where you want the 
copper stripped from the board. 
Leave behind the parts where you 
want to protect the copper. 

• Some services will weed the 
sticker for you; others may not. 
When we ordered some from TAP 
Plastics, they came back weeded. 

• Most vinyl cutters come with fancy, 
sharp tweezers, but you can use a 
utility knife or a pushpin taped into 
the barrel of an old pen to pick out 
the parts of the vinyl you don't 
want. 

• IMPORTANT: Double-check 
that your design is the right I 
size, and that you left all the 
correct parts on the sticker when 
you weeded it! 



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Step 4 — Transfer the vinyl to the copper board. 






• Scuff the board so the etchant will be able to reach the copper easily. Circuit board blanks 
are treated with a clear coating that keeps the copper from oxidizing in the air. If this 
coating has been removed for any amount of time, you'll see dark spots. These spots 
shouldn't affect your etching. 

• Place your weeded sticker on a flat surface and cover it with low-tack transfer tape or 
masking tape. If you use very sticky tape, the vinyl won't stay on your circuit board. 

• Use the transfer tape to lift your vinyl sticker off its backing and place it onto the copper 
face of the board. Smooth it down firmly everywhere to get the best adhesion you can. 
Then remove the transfer tape. 



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Step 5 — Prepare the etchant bath. 




• Put your etchant into a nonmetallic tray or jar with a tight-fitting lid. 

• Wear safety goggles and rubber or vinyl gloves, to keep the etchant chemicals out of your 
eyes and off your skin. 

• Most people use ferric chloride. Other chemicals will also work, such as muriatic 
(hydrochloric) acid and hydrogen peroxide. For detailed tutorials on both methods check 
out MAKE's Circuit Skills: Circuit Board Etching video and The Real Elliot's tutorial on 
Instructables . 



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Step 6 — Etch the circuit board. 




• Immerse the circuit board in the bath of etchant. Agitate the board from time to time, to 
keep fresh etchant working on the copper. 

• Remove the board frequently to check its progress. If you etch for too long, you could etch 
away the circuit traces. However, over-etching is much less likely with this technique, 
since the vinyl makes a very tight bond with the board. 

• It's done when the copper is completely removed from the areas not covered by vinyl. 
Take the board out of the etchant and rinse it under cold running water. 

• Using a smaller container will help you to use less liquid and still cover the 
board. 

• If your etching liquid is warm, it will act faster on the copper, reducing your etching time. 
You can prepare a warming tray filled with hot water, and place your etching tray or jar 
in it to raise the temperature. Make sure you don't overheat it. 

• If you etch in a small jar, you can seal the lid and shake it gently to agitate it with less 
risk of spilling. 



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Step 7 — Peel the vinyl off. 




• Once you're sure the copper is cleared to your satisfaction, peel the vinyl resist off the 
board. It should come off easily. 

• If you really need to etch it some more, you can, but placing the vinyl back on may be a 
challenge. It's best to leave the vinyl on until you're sure the copper is removed. 

• Admire your new circuit board. 



Step 8 — Use your new circuit board. 




• Compare your circuit board to the 
original artwork. If everything is to 
your satisfaction, you can now drill 
out the holes for your components 
or surface mount them as we did. 

• Grab this robot circuit board design 
at 

http://makezine.com/go/robotresist 
and etch your own. Then follow the 
directions there to solder a 
flashing-eyed robot circuit! 



This project first appeared in MAKE Volume 33 . page 130. 

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st generated on 2013-01-31 02:52:22 PM. 



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